In general, in a high speed communication for data transmission in the GHz range, a differential serial interface has been used to avoid crosstalk and noise coupling generated in a parallel interface. The differential serial interface is mainly constructed with a comparator circuit.
Typically, the comparator circuit receives two input signals, compares voltages thereof, and generates an output signal in response to a comparison result. A differential voltage comparator is a type of comparator for comparing two differential input signal voltages and outputting a differential output.
For example, the differential comparator may be used to detect squelch or un-squelch of a receiving unit for receiving input signals. The receiving unit is connected to a communication line or a bus, and determines whether a real signal exists on the communication line. Referring to the Serial ATA Specification, a signal speed and a signal threshold range should be 1.5 Gbps and 50˜200 mV, respectively. In signal detection according to the Serial ATA specification, since the signal speed is high and the signal voltage is small, it is difficult to implement the comparator circuit by conventional techniques. Although this can be achieved, the implementation results in high power consumption, which is worsened when the signal speed is increased to 2, 3, and 10 Gbps.